Re: Multicast testing
Not sure if you got an answer yet. you don't say what version of
iperf you are running. at least some of the 2.x versions don't
implement the -T flag correctly and no matter what you think you set
it to it goes to "1".
I know the 1.71 version supports it correctly. I'm also not recalling
at the moment if you need -T on both sides or just the client, so you
might try that as well.
On Nov 30, 2006, at 10:51, Mike Lancaster wrote:
I'm testing that multicast sent from one machine is being forwarded
to another subnet. Could anyone explain to me what is happening
and why?
I start an iperf server on machine A which is on subnet A.
/tmp/iperf_rhel4 -s -u -B 231.1.84.21 -i 1 -p 26240
Output is;
------------------------------------------------------------
Server listening on UDP port 26240
Binding to local address 231.1.84.21
Joining multicast group 231.1.84.21
Receiving 1470 byte datagrams
UDP buffer size: 256 KByte (default)
------------------------------------------------------------
I start a client on machine B which is on subnet B
/tmp/iperf_rhel4 -c 231.1.84.21 -u -T 32 -t 9999 -i1 -p 26240
Output is;
------------------------------------------------------------
Client connecting to 231.1.84.21, UDP port 26240
Sending 1470 byte datagrams
Setting multicast TTL to 32
UDP buffer size: 108 KByte (default)
------------------------------------------------------------
[ 3] local <machine A> port 18218 connected with 231.1.84.21 port
26240
[ 3] 0.0- 1.0 sec 129 KBytes 1.06 Mbits/sec
[ 3] 1.0- 2.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 2.0- 3.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 3.0- 4.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 4.0- 5.0 sec 128 KBytes 1.05 Mbits/sec
Nothing is received on the server on machine A
If I then run tcpdump in another session on machine A (tcpdump host
231.1.84.21) I get output in the server window;
[ 3] local 231.1.84.21 port 26240 connected with <machine A> port
18224
[ 3] 0.0- 1.0 sec 128 KBytes 1.05 Mbits/sec 0.739 ms 254/
343 (74%)
[ 3] 1.0- 2.0 sec 128 KBytes 1.05 Mbits/sec 0.550 ms 0/
89 (0%)
[ 3] 2.0- 3.0 sec 128 KBytes 1.05 Mbits/sec 0.608 ms 0/
89 (0%)
[ 3] 3.0- 4.0 sec 129 KBytes 1.06 Mbits/sec 0.628 ms 0/
90 (0%)
[ 3] 4.0- 5.0 sec 128 KBytes 1.05 Mbits/sec 0.632 ms 0/
89 (0%)
[ 3] 0.0- 5.8 sec 742 KBytes 1.05 Mbits/sec 0.648 ms 254/
771 (33%)
Does iperf not join the stream? Is this why I don't get output
until tc
o do with tcpdump putting the network interface into promiscuous mode?
Thanks in advance for any help,
Mike
___________________________________________________________
Now you can scan emails quickly with a reading pane. Get the new
Yahoo! Mail. http://uk.docs.yahoo.com/nowyoucan.html
-----
-debbie
Debbie Fligor, n9dn Network Engineer, CITES, Univ. of Il
email: fligor --at-- uiuc.edu <http://www.uiuc.edu/ph/www/fligor>
"Every keystroke can be monitored. And the computers never forget."